Examples of a pharmaceutical used for treatment of hypertension include various neuroleptics acting on the neural-factor-related regulator system, ACE inhibitors acting on the heurohumoral-factor-related regulator system, AT receptor antagonists, Ca antagonists acting on the vascular-endothelium-derived-substance-related regulator system, and hypotensive diuretics acting on the body-fluid-regulator system in the kidney. These pharmaceuticals are mainly used in medical institutions for patients suffering from severe hypertension.
Under the present state, however, pharmaceuticals used as a measure against hypertension are a serious burden for patients because in spite of satisfactory effectiveness, their side effects are not a few.
In the case where hypertension is regarded as a life-style related disease, on the other hand, general therapies for improving the life style such as dietetic therapy, kinesitherapy and limitation of alcoholic intake or smoking are applied widely not only to the people having a high normal blood pressure including a mild case but also to patients suffering from severe hypertension. With a tendency to recognize the importance of general therapies, improvement of eating habits has received great attention. Since there exist a large number of foods having blood pressure lowering action, pressure reducing materials derived from foods have so far been briskly searched for and separation and identification of their effective ingredients have been carried out frequently.
Under such situations, there is an increasing demand for the development of a method for preventing, ameliorating or treating hypertension without depending on pharmaceuticals if possible. As such a method, dietetic therapy is particularly important, so that foods having blood pressure lowering effects or blood-pressure-rise inhibitory effects have briskly been searched for. Proposed is use of, as a hypotensor, the juice of an unripe fruit of apples, pears, peaches or like fruits belonging to the family Rosaceae which juice contains fruit polyphenol such as caffeic acid having angiotensin I converting enzyme (ACE) inhibiting action (Japanese Patent Application Laid-Open (Kokai) No. Hei 8-259453). It is also reported that a water extract of sugarcane root tuber contains a chlorogenic acid, which is a polyphenol, and it has ACE inhibitory action (Food Research Results Information, No. 9, 20–21(1997)).
Foods which are said to have pressure reducing effects or their effective ingredients, however, tend to be not always satisfactory in their effectiveness, intake frequency or taste upon intake and in addition, many of them do not start exhibition of blood pressure lowering effects soon after intake.
An object of the present invention is therefore to provide a preventive, alleviative or remedy for hypertension which is derived from plants or foods, has excellent safety, does not become a burden for patients when administered daily and orally, and has high antihypertensive action.